An enzyme-linked immunosorbent assay has been developed for the direct assay of cortisol in the saliva of man, sheep, calf and pig. The assay is sensitive (integral of 1pg), highly specific and reproducible, and has the advantage over radioimmunoassay in being cheaper and quicker to carry out. The relatively-non invasive method of collecting saliva on cotton buds coupled with simple assay equipment provide a good potential for assessing cortisol status in studies on stress and welfare in farm animals as well as the possibility of monitoring cortisol status in mammals generally.